Nanoparticle could kill cancerous lymphoma cells, study says

Northwestern University researchers said they have discovered a nanoparticle that could be the basis for a nontoxic way to eliminate cancerous lymphoma from the body.

The nanoparticle, which the researchers tested in cell cultures and on mice, fools the lymphoma cells into thinking it contains high-density lipoprotein (HDL), which the cells need to survive.

The nanoparticle has a similar shape, chemistry and size as high-density lipoprotein, but it has a tiny gold particle at its core. The function of high-density lipoprotein is to carry cholesterol in the bloodstream.

All of the cells in the human body need cholesterol to survive, said Dr. C. Shad Thaxton, an assistant professor of urology at Northwestern University Feinberg School of Medicine and co-senior author of the study. "Cancerous B (lymphoma) cells have an increased need for cholesterol, and it's deadly to deprive them of this."

"B cells have a receptor for HDL on their surface, and we found that the nanoparticles bind to the specific cell receptors, and starve the cells of cholesterol. Then, because the nanoparticles starve them, (specific) B cells die," Thaxton said.

The nanoparticle pulls a one-two punch, said the researchers, whose paper on their work was published in the Jan. 21 edition of the Proceedings of the National Academy of Sciences.

"We think the particles stick to the cell and pull the cholesterol out of the membrane," said Dr. Leo I. Gordon, a professor of medicine-hematology/oncology at Northwestern and the study's co-senior author.

The particles also prevent cholesterol from entering the cell, Gordon said.

"Instead of a mouthful of cholesterol, they (the lymphoma cells) get a mouthful of gold," he said. "They (the nanoparticles) prevent cholesterol from entering the (lymphoma) cell, and the consequence is that there is a net loss of cholesterol out of the cell, and not enough cholesterol is made to keep the cell going."

The number of non-Hodgkin lymphoma diagnoses in the United States is expected to hit nearly 70,000 in 2013, according to the National Cancer Institute at the National Institutes of Health. About 85 percent of non-Hodgkin lymphomas are B-cell lymphomas, according to the Lymphoma Research Foundation.

When a lymphocyte, a type of white blood cell, grows abnormally, a lymphoma occurs.

Dr. Thomas E. Witzig, professor of medicine at the Mayo School of Graduate Medical Education in Minnesota, called the study "very well done."

"One needs to remember when reviewing this type of report that, although this is a very interesting concept, the studies they describe with their HDL nanoparticles have not yet been conducted in humans," Witzig said. "Whether or not they will be able to achieve a high enough level of the nanoparticle in a lymphoma patient's bloodstream to actually make a dent in the tumor is yet to be determined but certainly worth exploring."